Indicating or control device



Jan. 30, 1951 K. P. GEORGE 2,539,575

INDICATING OR CONTROL DEVICE 2 Sheets-Sheet 2 K. P. GEORGE INDICATING ORCONTROL DEVICE Jan. 30, 1951 Filed Jan. l0, 1948 Patented Jan. 30, 19512,539,575 INDICA'IING 0R CONTROL DEVI-CE Kenyon P. George, SouthPasadena, Calif, assignor to Beckman Instruments, Inc., a corporation ofCalifornia Application January 10, 1948, Serial No. 1,557

(Cl. 11G-133) 13 Claims.

My invention relates in general` to position indicating or controllingdevices and, more particularly, to a device fcr use in connection with arotatable object to indicate and control the angular position of such anobject, or the position of another object connected thereto. For eX-ample, my invention may take the form of a gearcontaining knob which maybe used in connection with a shaft to control the angular position ofthe shaft and to indicate its angular position, i. e., the number ofrevolutions and/or fraction of a revolution through which the shaft hasbeen rotated, or which may be used to indicate or control the angularposition of an object carried by the shaft, o1' the position of anobject which drives or is driven by the shaft.

My invention finds particular utility when used in connection with suchdevices as variable resistors, inductors and capacitors, for example,and I prefer to consider herein an application of my invention to avariable resistoi` for convenience in eiecting a disclosure thereof.However, as will be readily apparent to those skilled in the art, theinvention is susceptible to various other applications and it willtherefore be understood that I do not intend to be limited to thespecific application disclosed herein for purposes of illustration.

An important object of the invention is to provide a device which is notonly adapted to be used in connection with a shaft, such as the shaft ofa variable resistor, for example, to indicate the angular positionthereof, but which is also adapted to be used to rotate the shaft tocontrol the angular position thereof. A related object is to providesuch a device having both a manually operable control knob for varyingthe angular position of the shaft or other object with which it isassociated and also an indicating means for showing accurately theangular position.

Another object oi the invention is to provide a device of the foregoingcharacter having two indicators, hereinafter termed the revolution and v2 which is used in making accurate readings or adjustments, i. e., thefraction indicator, is not subject to any gear backlash, which is animportant feature of the invention.

A further obj ect is to provide a device wherein the two indicators areconnected by a differential gear system in such a manner that thefraction indicator, when rotated through one complete revolution, drivesthe revolution indicator through a fraction of a revolution.

Still another object is to provide an indicating device of the foregoinggeneral character wherein the differential gear system includesconcentric first and second gears having a third gear meshed therewith,the rst and second gears having different numbers of teeth thereon andthe rst lgear being stationary so that engagement of the teeth on thethird gear with successive ones of the teeth on the first and secondgears results in rotation of the second gear with respect to the firstgear. An important object in this connectionis to provide a devicewherein the revolution indicator is connected to the second gear andwherein the third gear is carried by the fraction indicator.

Still another important object of my invention is to provide anindicating device in which a knob or other drive means carries theaforesaid thirdl gear, also to provide such an arrangement in which thethird gear is pivoted on an axis which is nonparallel to the axis of thefirst and second gears and which preferably extends generally outwardlyrelative to the axis of the first and second gears.

An additional object is to provide ra stationary gear which is adaptedto be threadedly connected to a suitable Support and which is providedwith means thereon for the reception .of a tool for threadedlyconnecting it tc the support.

A further object is to provide an indicating `de-v vice of the`character hereinbefore described wherein the two indicators may eitherbe dials having circular scales thereon, or may be provided withpointers which are adapted to move the utilization of the exemplaryembodiments ofi the invention which are illustrated in the ac- 3companying drawings and which are described in detail hereinafter.Referring to the drawings:

Fig. 1 is a sectional view illustrating an indicating and controllingdevice Which represents the presently preferred embodiment of myinvention as used in connection with a variable resistor;

Figs. 2 and 3 are sectional views which are taken along the broken lines2 2 and 3--3, respectively, of Fig. 1;

Fig. 4 is a sectional View illustrating another embodiment of theinvention;

Fig. 5 is a front elevational view of the device illustrated in Fig. 4;

Fig. 6 is a sectional View illustrating a third embodiment of myinvention;

Figs. 7 and 8 are sectional views which are taken along the broken linesl-i and 8 8, respectively, of Fig. 6 and Fig. 9 is a front elevationalview of the device illustrated in Fig. 6.

Referring particularly to Fig. 1 of the drawings, I show one embodimentof my indicating and controlling device, indicated generally by thenumeral lll, used in connection with a variable resistor il which, perse, forms no part of the present invention. The resistor il isdiagrammatically shown as including a cylindrical housing l2 which isprovided with a shallow,

helical groove i3 therein to receive the major turns of a helical, woundresistance element i4, the resistance element being shown as having tencomplete major turns, although any desired number of such turns may beemployed. Each major turn comprises a large number of minor turns Mawound helically around a core Mb. Molded or otherwise secured to one endof the housing i2 is an externally threaded fitting l5 which is adaptedto project through an opening I6 in a panel Il, the opposite end of thehousing being closed by la cover i6. J ournalled in a bore 2l in thefitting i5 is a shaft 22 having annular grooves therein for split rings23, or the like, the latter being adapted to seat against the ends ofthe tting to prevent axial movement of the shaft.

The shaft 22 carries a collar 2li which is slidable longitudinally ofthe shaft, but which is prevented from' rotating relative to the shaftby a pin 25 extending into a longitudinal groove 26 in the shaft. Thecollar 24 is provided with an arm 2 having thereon a grooved contact 28which partially encircles the resistance element I4, this Contact beingadapted to slide along the helical resistance element as the shaft 22 isrotated so as to move the collar 2li longitudinally of the shaft. Itwill be apparent that as the shaft 22 is rotated in the clockwisedirection, as viewed in Fig. 2 of the drawings, the contact 28 willfollow the turns of the resistance element I4 to move the collar 2daxially from right to left, as viewed in Fig. l. Conversely, by rotatingthe shaft 22 in the counterclockwise direction, as viewed in Fig. 2, thecollar 24 may be moved from left to right, as viewed in Fig. 1. Suchaxial movement of the collar 24 is limited by stops 29 and 3i) which aremounted on the inner surfaces of the end walls of the cylindricalhousing i2 in the path of the arm 21 in positions such that they limitmovement of the sliding contact 28 beyond the corresponding ends of thehelical resistance element I4.

The variable resistor il may be incorporated in an electrical circuitwhose resistance is to be varied by means of suitable connections (notshown) to the sliding contact 28 and one end of the helical resistanceelement le, e. g., the right end of the resistance element as Viewed inFig. 1. Alternatively, the 'resistor H may be connected as apotentiometer. Thus, the resistance provided by the variable resistor ii depends upon the position of the sliding contact 28, the resistancefrom one end being a minimum when the sliding contact is in one extremeposition and being a maximum when it is in the other eXtreme position.It will be apparent that in Order to determine the resistance offered bythe variable resistor ii, it is necessary to determine the position ofthe sliding contact 28 on the resistance element I4. This may beaccomplished by determining the number of revolutions and/or fraction ofa revolution through which the shaft 22 has been rotated, which is thefunction of the indicating device i8 in the particular applicationillustrated.

As best shown in Fig. 1 of the drawings, the device l) includes ive maincomponents, viz., an indexing plate 34 which is adapted to seat againstthe front face of the panel Il, a first, stationary gear or gear member35 which is adapted to be threadedly connected to the fitting l5, asecond gear or gear member 36 which is carried by and is rotatablerelative to the stationary gear member, an actuating member 3l(exemplified as a knob) which is adapted to be rigidly connected to theshaft 22 so as to be rotatable therewith relative to the gear members 35and 36, and a third, idling gear 33 which is carried by the actuatingmember and which is meshed with the gear members 35 and 36, the latterhaving diiierent numbers of teeth thereon so that the idling gear 38causes the gear member 3@ to rotate relative to the stationary gearmember 35 upon rotation of the actuating member as will be discussed inmore detail hereinafter. The device IU also includes first and secondindicating means or indicators 39 and it which are exemplied as carriedby the gear member 36 and the actuating member 31, respectively, andwhich are adapted to cooperate with a pointer li on the indexing plate34 to indicate the number of revolutions and/or fraction of a revolutionthro-ugh which the sliding contact 28 has been rotated from a given orend position, the indicators being dials having circular scales thereonin the particular embodiment illustrated in Figs. 1 to 3.

Considering the indicating and controlling device i in more detail, thestationary gear member 35 is provided with a boss 43 which projectsthrough a central opening 44 in the indexing plate 34 into the opening i6 in the panel l1, and is provided with a threaded bore 6.5 which isadapted to receive the externally threaded fitting I5, the stationarygear member also having a iiange 46 thereon which is disposed in acentral recess 41 in the indexing plate when the indicating device isassembled. it will be noted that when the stationary gear member 35 istightly threaded on the fitting i5, the ange 48 thereon bears againstthe indexing plate 34 to clamp it to the panel Il so that it isunnecessary to provide additional means for securing the indexing plateto the panel. It will also be apparent that the stationary gear member35 and the fitting l5 cooperate to clamp the variable resistor l i tothe vpanel I1, as well as to clamp the indexing plate 3ft thereto. Inorder to facilitate tightening of the stationary gear member 35 on theiitting I5, the flange 4t is formed to receive a suitable tool, thispreferably being accomplished by making the flange hex- S agonal, asbest shown in Figi. 2, to permit applica.e tion of a wrench thereto.

The stationary gear member 35 is provided with a cylindrical portion Uwhich extends into a bore 5 I in a sleeve portion 52 of the gear member36, the latter being carried by and being adapted to rotate about thecylindrical portion 5U of the stationary gear member. The gear member 36is provided with a radial flange which, as will be discussed in moredetail hereinafter, forms the indicator or dial 39 and which isjournalled against the flange 46 on the stationary gear member 35 toprevent axial movement of the gear member 36 toward the right, as viewedin Fig. 1 of the drawings.

Formed on the forward end of the cylindrical portion 58 of thestationary gear member 35 are axially extending gear teeth 54, similargear teeth 55 being formed on the forward end of the sleeve portion 52of the second gear' member 35 and being disposed in the same radialplane as the teeth 54. Thus, the stationary gear member 35 and therotatable gear member 36 are, in eect, crown gears both of which aremeshed with the idling gear 38 carried by the actuating member 31.

As previously indicated, the teeth 54 on the stationary gear member 35differ in number from the teeth 55 on the gear member 36 so that theidling gear 38 will rotate the gear 36 upon rotation of the actuatingmember 31, the diierence 1 in the numbers of teeth depending upon theparticular apparatus with which the device III is employed, e. g., thevariable resistor II, and depending upon the nature of the dial 39carried by the gear member 36. Since, as previously discussed, thehelical resistance element I4 of the particular variable resistor IIVshown comprises ten complete turns, the device I U is preferably sodesigned that the gear member 36 and the dial 39 carried thereby rotateone-tenth of a revolution for each complete revolution of the actuatingmember 31 when the indicating device is used with the particularvariable resistor I I. In other words, as the actuating member 31 andshaft 22 are rotated through 360 so as to move the sliding contact 28along one full turn of the resistance element I4, the gear member 36 anddial 39 are preferably rotated through one-tenth of a revolution. rIhus,when the sliding contact 28 is moved from one end of the helicalresistance element I4 to the other by rotating the shaft 22 through tencomplete revolutions, by means of the actuating member 31 the gearmember 36 and dial 39 are rotated through one complete revolution.

The foregoing may be accomplished by providing the gear member 36 withten teeth 55 for every nine teeth 54 on the stationary gear member 35 ifrotation of the gear member 36 and dial 39 in the same direction as theactuating member 31 is desired. If counter-rotation of the gear member36 and actuating gear member 31 is desired, this may be accomplished byproviding the stationary gear member 35 with eleven teeth and the gearmember 36 with ten teeth. In the particular construction illustrated inthe drawings, the stationary gear member 35 is provided withtwenty-seven teeth 54 and the gear member 36 is provided with thirtyteeth 55. However, I do not desire to be limited to any' specic numbersof teeth for the gear members 35 and 36 since the numbers of teeth maybe varied as hereinbefore discussed as long as the proper ratio ismaintained, although it is advantageous to use relatively large numbersof' teeth on the gear members 35 and 36 since this permits the use of asmaller idling gear 38. It is distinctly preferable to dispose thelarger number of teeth on the outer gear member 36. The arrangement ofthe invention is such that the circular pitch on each gear member can beequal so that a single idling gear meshing therewith can be used, thuseliminating backlash and insuring extreme accuracy of the indications.

It will be apparent that since the teeth 54 and 55 on the gear members35 and 36 differ in number, the gear member 36 will be rotated by theidling gear 38 as the teeth on the latter mesh with successive ones ofthe teeth on the gear members 35 and 36 upon rotation of the actuatingmember 31. Thus, with the ten to nine ratio hereinbefore discussed, thegear member 36 will be rotated through an angle corresponding to thespacing of the teeth 55 thereon, i. e., one-tenth of a completerevolution, for each complete revolution of the actuating member 31.

In the particular construction illustrated in Figs. l to 3 of thedrawings, the actuating member 31 is a knob which is preferably knurled,as indicated at 58, for convenience in manipulation, and which isadapted to be rigidly connected to the shaft 22 by a set screw 59threaded into a bore in the knob, the shaft being provided with a flat6I against which the set screw is adapted to bear. The knob 31 isprovided with a recess 62 therein which receives the sleeve portion 52of the gear member 36 and is provided With an annular groove 63 in thebase of this recess into which the teeth 54 and 55 on the gear members35 and 36 extend, the idling gear 38 being disposed in a cavity 64 inthe knob which communicates with the groove 63 and being rotativelymounted on a pin 65 which eX- tends through this cavity, as best shownin Figs. 1 and 3.

One of the important concepts of theinvention is to associate the idlinggear 3B with the knob or actuating member 31. Another important conceptis the mounting of the idling gear 38 to revolve about the common axisof the gear members 35 and 36 while rotating about the axis of the pin65. In these connections, the invention comprehends an indicating devicein which the axis of rotation of the idling gear 38 shall benon-parallel to the common axis of the gear members 35 and 36. In Figs.1 to 3 the journalling pin 65 is shown as radially disposed but itshould be understood that any outwardlyextending pin position can beused by which term I have reference not only to the radial positionshown but also to other non-radial positions in which the pin axis is inthe plane of the paper as viewed in Fig. land to other non-radialpositions in which the pin axis is tangential to a circle drawn aboutthe common axis of the gear members 35 and 36. The concepts mentioned inthis paragraph are of particular importance if compactness is desiredand result in the possibility of manufacturing an indicating and controldevice of much smaller size and greater simplicity than heretoforeavailable.

As best shown in Fig. 2 of the drawings, the dial 39 carried by the gearmember 36 is formed on the flange 53 thereof and is divided into tenequal parts, the divisions being indicated by indicia 10, 1I, 12, 13,etc., which are identified by the numerals 0, 1, 2, 3, etc. The dial 39may be read with reference to any suit` .able reference, e. g., thepointer di which is carried by the indexing platey 34, the pointer beingsecured to the indexing plate by screws 83 or the like.

The dial 40 carried by the knob 3l is preferably formed on a skirt 85 ofthe knob and is concentric with but of smaller diameter than the dial 39so that it may also be read with reference to the pointer 4l. As bestshown in Fig. 2 of the drawings, the dial i0 is divided into ten equalmajor parts, the major divisions being indicated by indicia 90, 9|, 92,93, etc., having the numerals 0, 10, 20, 30, etc., thereadjacent. Inaddition, each major division of the dial 40 is divided into ten equalminor parts, each minor division being indicated by an indicium I, Thus,the indicia 95, 9|, 92, etc., on the dial iii represent tenths of arevolution of this dial and the indicia H thereon .represent hundredthsof a revolution,

Considering the operation of the device it, as the knob 3l is rotated todrive the shaft 22 and thus move the sliding contact 23 along thehelical :resistance element l, the dial 39 carried by the :gear member36 will be driven at one-tenth the Yspeed of the dial 130 through thecooperation of the gear members 35 and 3S and the idling gear 38 in themanner previously discussed. In other Words, as the knob 31 and its dialiii are rotated through one complete revolution to move the slidingcontact 28 around one full turn of the helical resistance element I4,the gear member 35 and its dial 39 will be rotated through one-tenth ofa revolution, it being understood that this :1

' speed ratio will be obtained onlf,7 when the specific tooth ratiodiscussed previously herein is employed and that other speed ratios maybe obtained by using other tooth ratios. Thus, it will be apparent thatthe numerals on the dial 39 will indicate the number of completerevolutions through which the sliding contact 2t has been moved and thatthe numerals on the dial di] will indicate any fraction of a revolutionthrough which it has been rotated, the fraction of a revolution beingexpressed decimally. For example,

with the sliding contact 28 in approximately the position shown in Fig.1 of the drawings, the device l shows, referrin to Fig. 2, that thesliding contact has been moved through 5.50 revolutions from the rightend of the helicai resistance element I d, as viewed in Fig. l.

It will be understood that although I have shown the dials 39 and t@ asbeing calibrated in terms of revolutions and fractions of revolutions,these dials may be calibrated in any suitable units. For example, whenthe indicating and controlling device l0 is used with the variableresistor l l, the dials 39 and dii may be calibrated in ohms if desired.

One feature of the present invention resides in the ease with which thedevice l ii and variable resistor Il may be assembled and mounted on thepanel i1. As previously pointed out, in order to mount the variableresistor i i and the indexing plate 34 of the indicating device i0 onthe panel, it -is merely necessary to thread the stationary gear member35 on the iitting l5 and to tighten it by applying a wrench or othersuitable tool to the hexagonal periphery of the iiange i5 thereon.Subsequently, the gear member 35 may be telescoped over the cylindricalportion 5@ of the stationary gear member 35, it being necessary toinstall the pointer lil after the gear member 35 has been positioned.The assembly of the indicating device I0 may then be completed by f'dicating and controlling device slipping the knob 3l over the forwardend of the shaft 22 and securing it thereto by means of the set screw59. Thus,y all moving parts of the indicating device l0 may be installedafter the stationary gear member 35 has been threaded on the fitting I5and tightened, which is an important feature of the invention. However,it will be understood that I do not intend to be limited to the specicinstallation shown in Fig. 1 of the drawings since the indicating deviceiii may be mounted in a similar manner when used with devices otherthanthe variable resistor Il, and may also be mounted in various othermanners.

In Figs. 4 and 5 of the drawings, I show an in- Mil which is similar tothe previously described device i0, the principal diierence between thedevices l0 and i I0 being that the latter is provided with an indexingplate l il and indicators H2 and l i3 which correspond to but differ inconstruction from the indexing plate 3d and indicators 3S) and i0 of thedevice iti. With the foregoing exceptions, the indicating andcontrolling devices l@ and lli] are substantiaily identical and theremaining components of the latter are identified by the same numeralswhich were used to identify corresponding components of the device iii.

As best shown in Fig. 5 of the drawings, the indexing plate ii l,instead of being provided with a pointer such as the pointer il on theindexing plate all, is provided with a dial having indicia E20, l2l,E22, 23, etc., thereon which are numbered 0, "1, 2, "3, etcrespectively. The indicators H2 and. H3, instead of being dials as inthe indicating device iii, are pointers which are carried by the gearmember 35 and the knob 3'1, respectively, and which are movable over thedial on the indexing plate l i l. Thus, the pointer l I2 indicates thenumber of complete revolutions through which the knob 3l has beenrotated and the pointer H3 indicates any fraction of a revolutionthrough which it has been rotated, the operation of the device i l0otherwise being identical to that of the device le.

In Figs. 6 to 9 of the drawings, I show an indieating and controllingdevice Mil which, basically, is substantially identical to the deviceH0, the only differences being in the structural details. Referringparticularly to Fig. 6 of the drawings, the device Mc also includes vemain components, viz., an indexing plate MI which is adapted to seatagainst the front face of the panel ll and which is provided with a dialthereon, a stationary gear or gear member 42 which is adapted to bethreadedly connected to the fitting i5, a second gear or gear member M3which is carried by and is rotatable relative to the stationary gearmember, an actuating member |44 (exemplified as a knob) which is adaptedto be rigidly connected to the shaft 22 so as to be r0- tatabletherewith relative to the gear members M2 and 43, and an idling gear M5which is carried by the knob |44 and which is meshed with the gearmembers U32 and l 133, the latter having different numbers of teeththereon so that the idling gear causes the gear member 143 to rotaterelative to the stationary gear member |42 upon rotation of the knob,all as hereinbefore described. The device Ulli also includes first andsecond indicators M5 and Ml (exemplified as pointers) which are carriedby the gear member M3 and the knob E44, respectively, and which areadapted to move around the dial on the indexing plate MI to indicate thenumber of revolutions and/or fraction of a revolution through 9 whichthe knob |44 and shaft 22 have been rotated.

Considering the indicating and controlling device I4Il in more detail,the stationary gear member |42 is provided with a threaded bore |50which is adapted to receive the externally threaded fitting I5, and isadapted to seat against the front face of the panel i1 when tightlythreaded on the fitting I5. In the embodiment shown in Figs. 6 to 9 ofthe drawings, the indexing plate or dial |4| is not clamped to the frontface of the panel I1 by the stationary gear member |42, as is the casewith the indexing plate 34 of the indicating device IU, but is adaptedto be mounted on the front face of the panel I1 by any suitable means(not shown) such as screws, or the like. The stationary gear member |42is provided with a cylindrical portion |5| which is disposed in a bore|52 in a sleeve portion |53 of the gear member |43, the latter beingcarried by and being adapted to rotate about the cylindrical portion I5|of the stationary gear member. The gear member |43 is provided with ashoulder |54 which is adapted to engage a complementary shoulder |55 onthe stationary gear member |42 to retain the gear member |43 on thestationary gear member. It will be apparent that with this construction,the gear member |43 must be mounted on the stationary gear member |42before the latter is threaded i on the fitting I5, whereas in thedevices I and III), the gear member 36 may be mounted on the stationarygear member 35 after the latter has been threaded on the tting I5, whichis an advantage of the devices IU and IIO over the device |40.

Formed on the forward end of the cylindrical portion II of thestationary gear member |42 are axially extending gear teeth |58, similargear teeth |59 being formed on the forward end of the sleeve portion |53of the rotatable gear member |43 and in substantially the same radialplane as the teeth |58. As is the case with the teeth 54 and 55 on thegear members 35 and 36, the teeth |58 on the stationary gear member |42differ in number from the teeth |59 on the rotatable gear member |43 sothat the idling gear |45 will rotate the gear member |43 in a mannersimilar to that described previously upon rotation of the knob |44. Ashereinbefore discussed, the diierence in the numbers of teeth on thegear members |42 and |43 depends upon the particular apparatus withwhich the indicating and controlling device |43 is to be used and may bevaried as required to provide any desired ratio between the rotationalspeeds of the gear member |43 and the knob |44.

The knob |44 of the device |40 is substantially identical to the knob 31of the devices II] and III), the knob |44 being adapted to be rigidlyconnected to the shaft 22 by a set screw |60 threaded into a bore ISI inthe knob and being adapted to bear against the flat 6| on the shaft. Theknob |44 is provided with a recess |52 therein which receives the sleeveportion |53 of the rotatable gear member I 43 and is provided with acavity |63 therein which communicates with this recess and receives theidling gear |45, the latter being rotatably mounted on an outwardlyextending pin |64 which extends through this cavity, as best shown inFigs. 6 and 8, and being meshed with the gear members |42 and |43.

As best shown in Fig. 6 of the drawings, the pointer I 46 carried by therotatable gear member |43 extends radially lirom the sleeve portion |53thereof and is adapted to move over the dial on. the indexing plate |4I.The pointer |41 carried by the knob |44 extends radially from a skirt|65 of the knob and is spaced forwardly from the pointer |45 on the gearmember |43, the pointer |41 also being movable over the dial on theindexing plate |4I. The dial on the indexing plate is similar to thedial on the indexing plate I I of the indicating and controlling device||0 and, in the particular construction illustrated, is also dividedinto ten equal parts, these divisions being indicated by indicia |10,ITI, |12-, |13, etc., having the numerals 0, "1, 2, 3, etc.,thereadjacent, respectively.

The operation of the indicating and controlling device |40 is identicalto that of the device IIB, the pointer |46 carried by the rotatable gearmember |43 indicating the number of complete revolutions of the knob 44and the pointer |41 carried by the knob indicating fractions ofrevolutions. As previously discussed, although the scales on the variousdevices disclosed herein are shown as calibrated in terms of revolutionsand fractions of revolutions, they may be calibrated in any desiredunits Without departing from the spirit of the invention.

Although I have illustrated the indicating and controlling devices i3,III! and |43 as being provided with manually operable knobs for rotatingthe shaft 22, it will be understood that the shaft may be driven invarious other ways and. may be power driven if desired. It will beapparent that the shaft 22 may also be driven from any point thereon andthat it may be driven in either direction since the differential gearsystems of the indicating devices are reversible. Further, it will benoted that since the indicators for indicating fractions of revolutions,viz., the indicator 40 ci the device II), the indicator I I3 of thedevice III), and the indicator |41 of the device |40, are adapted to berigidly connected to the shaft 22 or other rotatable object with whichthe devices are to be used, the indicators which are used in makingaccurate readings or adjustments are not subject to any lost motionwhich may arise through wear of the differential gear systems.

Although I have disclosed an exemplary application and Various exemplaryembodiments of my invention herein for purposes of illustration, it Willbe understood that the invention is susceptible to various otherapplications and that various changes, modifications and substitutionsmay be incorporated in the specic embodiments disclosed Withoutnecessarily departing from the spirit of the invention. Consequently, Ihereby reserve the right to the protection afforded by the full scope ofthe appended claims.

I claim as my invention:

l. In a device of the character described for use with a rotatableobject, the combination of: a first member provided with nrst indicatingmeans; means for rigidly connecting said iirst member' to the object soas to be rotatable therewith; a stationary gear having an axiscoinciding with the axis of rotation of the object; a second memberrotatable about said axis relative to said iirst member and saidstationary gear, said second member including a gear having teeththereon diiering in number from the teeth on said stationary gear, andsaid second member being provided with second indicating means; a thirdgear carried by said rst member and meshed with said stationary gear andsaid gear on said second member; and stationary indicatil ing meansadjacent and cooperating with said first and second indicating means.

v2. A device as set forth in claim 1 wherein said first and secondindicating means include concentric dials.

3. An indicating device as set forth in claim l wherein said first andsecond indicating means comprise pointers.

4. A device as set forth in claim 1 wherein said first member comprisesa knob.

5. In a device for indicating the position of an object which is adaptedto be driven by a rotatable shaft, the combination of: a firstindicating member providing an axis; means for rigidly connecting saidfirst indicating member to the shaft with its axis coinciding with theaxis of rotation of the shaft so as to render said first indicatingmember rotatable with the shaft; a stationary gear disposedsymmetrically about the axis of said first indicating member; a secondindicating member rotatable about the axis of said first indicatingmember relative to said first indicating member and said stationarygear, said second indicating member including a gear which is concentricwith said stationary gear and which is provided with teeth thereondiffering in number from the teeth on said stationary gear; and a thirdgear carried by and spaced from the axis of said first indicating memberand meshed with said stationary gear and said gear on said secondindicating member.

6. In a device of the character described, the combination of concentricfirst and second gears having different numbers of teeth thereon, saidfirst gear being stationary and being provided with a cylindricalportion, said second gear having a sleeve portion in which saidcylindrical portion of said first gear is disposed, said second gearbeing carried by and being rotatable about said cylindrical portion ofsaid first gear, said teeth on said first gear being formed on one endof said cylindrical portion thereof and said teeth on said second gearbeing formed on one end of said sleeve portion thereof, said ends beingdisposed in substantially the same plane; a third gear meshed with saidfirst and second gears; and means for moving said third gear along acircular path relative to said first and second gears so as to rotatesaid second gear about said cylindrical portion of said first gear.

7. In a device of the character described, the combination of:concentric first and second gears having a common axis and havingdifferent numbers of teeth thereon, said first gear being stationary andbeing provided with a cylindrical portion, said second gear having acomplementary bore in which said first gear is disposed, said secondgear being carried by and being rotatable about said .cylindricalportion of said first gear, and said second gear being provided withindicating means thereon; an actuating member rotatable relative to saidfirst and second gears about said common axis and provided withindicating means thereon; and a third gear carried by said actuatingmember and meshed with said first and second gears to be rotated by saidfirst gear in a manner to rotate said second gear upon rotation of saidactuating member.

8. A device as set forth in claim 7 wherein said actuating membercomprises a knob.

9. In a device of the character described, the combination of astationary gear provided with a threaded portion so as to be threadedlyconnectible to a support and having means thereon for the reception of atool for threadedly connecting it to the support; a second gearconcentric with and rotatable relative to said stationary gear, theteeth on said stationary gear and on said second gear differing innumber; an actuating member rotatable relative to said stationary gearand said second gear; and a third gear carried by said actuating memberand meshed with said stationary gear and said second gear so as torotate said second gear upon rotation of said actuating member.

10. In a device of the character described for turning a shaft, thecombination of a stationary gear; a rotatable gear having indicatingmeans thereon and having a number of teeth differing from the number ofteeth on said stationary gear; means for mounting said stationary androtatable gears with their axes common and in alignment with the axis ofsaid shaft; an actuating member having indicating means thereon andadapted to be connected to said shaft to rotate about said shaft axisand the common axis of said stationary and rotatable gears; an idlinggear; and means carried by said actuating member in its rotation forjournalling said idling gear to re? gear; a rotatable gear membercomprising a tubu-` lar portion having a toothed end comprising arotatable gear, said stationary and rotatable gears being concentric andbeing coaxial with respect to each other and to said shaft axis, thenumber of teeth on said stationary gear differing from the number ofteeth on said rotatableA gear; an actuating member rotatable about saidshaft axis and disposed immediately'forward of said stationary androtatable gears; a pin carried by said actuating member and providing aportion spaced from said shaft axis, said pin having an axis forward ofand traversing the teeth of both the stationary and movable gears; andan idling gear journalled on said portion of said pin and having teethsimultaneously meshing with the teeth of said stationary and rotatablegears.

12. In a device or" the character described for turning a shaft, thecombination of an outer gear adapted to be mounted coaxially with theshaft and having a plurality of teeth all facing substantially in thesaine direction; an inner gear coaxial with said outer gear andproviding teeth all facing in the same general direction as the teeth ofsaid outer gear, said outer gear having a different number of teeth thansaid inner gear; means for holding one of said gears stationary and forrotatably mounting the other of said gears to turn about the common axisof said gears; an actuating member rotatable about said common axis andsubstantially enclosing said gears; means for detachably connecting saidactuating member to the shaft; an idling gear; and means carried by saidactuating member in its rotation for `iournalling said idling gear torevolve about said shaft axis and to rotate about an axis non-parallelto said shaft axis, the axis of rotation of said idling gear beingspaced from and extending across the teeth of both the inner and outergears, said idling gear having teeth simultaneously meshing with theteeth ofsaid inner and outer gears.

13 13. A device as set forth in claim 9 including a support threadedlyconnected to said stationary gear, said support having a surface whichis adapted to engage one side of a wail means and said stationary gearhaving a surface which is adapted to engage the opposite side of theWall means so as to clamp the wall means between said surfaces when saidsupport and said stationary gear are threadedly connected.

KENYON P. GEORGE.

REFERENCES CITED The following references are of record in the le ofthis patent:

Number Number 14 UNITED STATES PATENTS Name Date Kronert May 28, 1912Burke Apr. 21, 1925 Thomas Dec. 3, 1929 Green et al Sept. 29, 1936 HallFeb. 24, 1942 Trbojevich Mar. 9, 1943 FOREIGN PATENTS Country DateFrance Oct. 16, 1926

